The inventive concept relates to piezoelectric energy harvesting devices and methods of fabricating the same and, more particularly, to flexible piezoelectric energy harvesting devices using piezoelectric lines or piezoelectric islands and methods of fabricating the same.
An energy harvesting technique converts wasted environmental energy into electrical energy to improve the energy efficiency of electronic products or electronic devices. Ultimately, the energy harvesting technique may enable stand-alone operation and/or self-charging of the electronic products or devices by using the environmental energy without additional supply of electrical energy.
If mechanical energy is applied to a piezoelectric material, the piezoelectric material generates electrical energy. Thus, an energy harvesting technique using the piezoelectric material converts the mechanical energy (e.g., force, pressure, and/or vibration) wasted in the circumference into the electrical energy available to us.
The energy harvesting technique using the piezoelectric material may use environmental energy sources such as the vibration of motors/pumps, human movement, the flow of water, and/or a wind to generate the electrical energy in a dark place without sunlight and/or at night.
However, a piezoelectric ceramic material used as piezoelectric material may have brittle and/or rigid properties. Thus, the piezoelectric ceramic material may be difficult to be applied to a device having a predetermined shape. Additionally, the piezoelectric ceramic material may have poor durability under shock or impulse.
Generally, a piezoelectric energy harvesting (PEH) device may include a piezoelectric wafer and a non-piezoelectric layer. The piezoelectric wafer may generate the electrical energy by vibration, pressure, sound, and/or deformation. The non-piezoelectric layer may be provided to supplement the brittle property of the piezoelectric material. The non-piezoelectric layer may include silicon, aluminum, copper, and/or a printed circuit board (PCB), etc. However, the combined structure of the piezoelectric material and the non-piezoelectric layer may have hardness, such that it may not be easily applied to application fields (e.g., the human body and/or clothes) requiring flexible properties.
A piezoelectric polymer has been suggested for resolving the above problems. However, the piezoelectric characteristics of the piezoelectric polymer may be very lower than that of the piezoelectric ceramic. Thus, the piezoelectric polymer may generate a low power of a few micro watt levels.